U.S. Pat. No. 8,891,681 (the '681 patent) describes a transmitter capable of switching between operation in a first mode which provides a vector-modulated RF output signal (also called digital IQ mode (DIQM)), and a second mode which provides a polar-modulated RF output signal (also called polar mode (PM)).
The polar transmit architecture offers a lower power consumption compared to IQ architectures, while high modulation bandwidths are easier achieved with IQ transmit architectures. However, it may be difficult to utilize a switchable architecture in order to achieve a good power consumption vs. design complexity tradeoff.